ST silver brazing operation manual
1. Roughing
The product includes the welding surface of the substrate and the ST workpiece, and the oxide layer on the surface to be silver brazed is removed by the method of volumetric processing.Before brazing, clean the brazing surface with alcohol to remove impurities that affect wetting, such as surface cutting fluid, so that the surface to be brazed is clean.
2. Preparation before welding
The silver solder is a single layer of silver solder with a thickness of 0.2mm (our company’s practical brand is HL312 strip), and the solder is cut into a shape similar to the brazing section; Use pure water (do not use direct water) and silver brazing flux to stir. Dilute the silver brazing flux with water to be close to a paste. If it is not easy to melt, you can properly heat the purified water (the practical brand of our company is QJ102).
Note: If the soldering area is large, double-layer silver solder can be used.
3. Brazing
When brazing, put the flaky silver solder into the paste-like silver solder, so that the upper and lower surfaces are coated with silver solder;
Brush a layer of paste-like silver solder on the iron-based brazing surface, then put on the flake silver solder filled with silver solder, and then put the ST workpiece to be soldered
Put the assembly into the induction coil to ensure that the weld is in the middle of the induction coil;
Start heating, the heating temperature is 750～800℃, when the edge of the silver solder overflows, rotate or slide the ST workpiece to ensure the contact area of the welding surface, press it tightly to remove the bubbles on the welding surface, and continue heating for a few seconds , Stop heating and take out the workpiece, complete welding.
4. Insulation of welded parts
After the silver brazing is completed, immediately bury the welding assembly in a heat preservation box containing quicklime, and then put the heat preservation box in a heating furnace that has been kept warm at 300°C for 24 hours to eliminate welding stress.
After the heat preservation is over, take out the workpiece and cool it at room temperature before proceeding to subsequent machining.
